Medusa (メドゥザ Meduza) is a female cyclops and a member of the Marines; having been stationed in the intimidating Marine base, G-6. She is the direct subordinate of her superior, Tombstone Grim, and as such, acts as the leader of G-6's 1st unit and second in command. Unlike Grim, Medusa seems less treacherous and more genuine in her desire to uphold justice. This contrast was made quite clear in how Medusa was left completely unaware of her superior officer's true intentions and nature.

She has eaten the Snake Snake Fruit, Model: Hornsman, allowing her to become a cycloptic-snake woman, as well as include venomous bites into her attacks. It was because of her Devil Fruit power and her impressive status amongst the G-6 officers that lead to Medusa being mistaken as and rumored to be the legendary Dragon of G-6 (タツのG6 Tatsu no G-Roku.)

Due to her cyclops anatomy, Medusa has several natural advantages she can rely on. Most prominently is her single eye, which functions in a manner similar to sonar; through outputting a form of electromagnetic radiation known as T-rays, which then bounce off her surroundings and return to her eye, thus giving her a clear image of what's ahead of her. This gives Medusa the amazing ability to see regardless of how bright or dim her environment is; thus maintaining near-perfect sight at all times. Medusa's eye also allows her to see through almost anything at will, making it difficult for others to fully avoid detection from Medusa's penetrating gaze. However, despite this amazing visual clarity, Medusa lacks the same field of view as humans and other races. Because of this, Medusa is forced to see only what's directly ahead of her. This causes Medusa to constantly turn her head from side to side when in need of scanning the immediate area.

As the cyclops lack a proper nose, Medusa uses her tongue to detect chemicals in the air; thus acting as her method of smelling the air around her. Since this is the same manner in which snakes determine the scents surrounding them, many of Medusa's comrades confuse this cycloptic trait for eccentricity on Medusa's part; believing she's purposefully imitating snakes due to her Zoan powers. Another function her mouth serves is the ability to spew a flammable liquid produced by her teeth. Through the act of gnashing her teeth, Medusa can combust the liquid. However, this is not useful at all for combat, as the fire created from the combustion can barely even warm the bodies of those who touch it. Instead, it is the cyclops' method of scaring away enemies, rather than resorting to violence. And even then, this combustible liquid can only be effectively used once a day.

Perhaps the second most reliable asset of Medusa's heritage are her cyclopsian muscles. Unlike those of humans and other races, which are designed for constant usage over long periods of time, Medusa's muscles are geared towards short bursts of immense strength and power at a time. As a result, Medusa sports the most potent muscular strength amongst all of G-6; even being said to rival that of Tombstone Grim when she unleashes her full might. Albeit, as she cannot use her full power all the time, she is limited to making use of this trait at very specific moments.

Aside from her heritage, Medusa is also a skilled combatant and military leader. Due to her culture's beliefs, Medusa is a highly trained Marine officer, both in and out of battle. She has learned to use Rokushiki, which adds to her natural strength and power. Furthermore, Medusa has eaten a Zoan Devil Fruit which grants her access to various snake-like abilities. Among these Zoan powers are the use of debilitating venom and agile movement, which she combines with her martial arts and cyclops abilities. Combined with her physical talents, Medusa has a strategic mind; seen in how she managed to counter the invasion of G-6 with her various ploys. Due to her strength and cunning, Medusa wound up becoming the second most dangerous officer within G-6; making her second only to her superior, Tombstone Grim.

Like other notable members of G-6, Medusa uses Rokushiki when in combat. While she has shown the ability to use other techniques, Medusa appears to specialize in the usage of Kami-e. Given her mixed physical prowess, combat experience and strategic wit, Medusa has shown a surprising talent for using Kami-e not only for defensive purposes, but for causing harm to opponents as well. Her most potent and lethal Rokushiki techniques however, are used while her Devil Fruit powers are active. By fusing her talent for Kami-e with her serpentine body, Medusa is almost untouchable in battle, and deceptively agile and quick. Medusa boasts the ability to almost always deal out more damage than she receives in a single fight through this manner.

Medusa possesses the powers of the Snake Snake Fruit, Model: Hornsman, and as such, can transform freely into a snake or snake-cyclops hybrid at will. Because she has Zoan powers, Medusa has learned to implement them in enhancing her cyclopsian biology and Rokushiki techniques. As a result, her techniques become much more powerful while transformed; with her Kami-e improving the most amongst Medusa's Rokushiki techniques. Combining Kami-e with her snake forms, Medusa can contort herself into a variety of different shapes for various purposes. This also makes it easier for Medusa to avoid nearly all forms of damage and still manage to harm others.

Medusa has also used her hybrid form to support her cyclopsian anatomy. The most obvious of her abilities being that by combining her snake venom with the flammable liquid in her mouth, Medusa can increase the combustibility of the liquid, making it far easier to produce harmful flames. In addition to this, Medusa's strength greatly increases. With her serpentine strength, Medusa can choke opponents through constriction and bite through stone. And when necessary, Medusa can unleash the full might of her cyclopsian strength in hybrid form to overwhelm or knock out foes in one hit, or create massive destruction in a short amount of time.

In animal-cyclops form, Medusa has shown that she can use her abilities outside of battle as well. Most notably is her power to extend and coil her body into different shapes, depending on situation present. For example, Medusa can traverse long distances quickly by twisting her tail into a spring and hopping from place to place. This can be further reinforced through the use of Geppo, allowing Medusa to propel herself like an arrow in mid-air. Another usage for her serpentine body can involve grappling on to ledges and columns, and then swinging through the air freely. There's also a technique Medusa developed, the Tekkai: Ouroboros, which turns Medusa into a wheel that allows her to quickly move forward in a straight line.

Medusa's name is derived from the legendary figure, Medusa; a woman who was transformed into a monstrous gorgon who could petrify anyone who met her gaze into stone. It's this focus on eyesight which is what made Wyvern 0m3g4 choose to give Medusa her name. Additionally, there is also the fact that Medusa ate the Snake Snake Fruit, Model: Hornsman, allowing her to become a snake. This also references the mythic Medusa, as she was identified with having snakes for hair.

As a member of G-6, Medusa has a monster motif surrounding her, much like the others. Given her name and Devil Fruit powers, Medusa has a clear connotation with the Greek myth of Medusa. Likewise, as she is a cyclops, Medusa also has an obvious cyclops theme as well. Finally, because of her serpentine appearance while transformed and natural ability to breathe fire, Medusa is constantly mistaken to be G-6's "dragon;" thus giving her a slight dragon motif as well.